A Bioreductive Protecting Group for RNA Synthesis

This protocol describes a method for the preparation of ribonucleoside phosphoramidite bearing a bioreductive protecting group on the 2'-OH group and its application in the synthesis of bioreduction-responsive oligonucleotides. The protecting group used in this method consists of the modified 4-nitrobenzyl skeleton, which has gem-dimethyl groups at benzylic positions to enable deprotection under physiological conditions. Applying the synthesized ribonucleoside phosphoramidite to solid-phase synthesis of oligonucleotides, a 2'-O-protected oligonucleotide was obtained without any undesirable cleavages under standard oligonucleotide synthesis conditions. The 2'-O-protected oligonucleotide was then treated with a combination of nitroreductase (Escherichia coli) and NADH as a bioreduction system for cleavage of the 2'-O-protecting group. After reduction of the nitro group, the protecting group was deprotected in a time-dependent manner. Thus, this protection technology is a potential new tool for production of reduction-responsive RNA-based materials that can be used in life and medical sciences. © 2021 Wiley Periodicals LLC. Basic Protocol 1: Synthesis of ribonucleoside phosphoramidite bearing a bioreductive protecting group Basic Protocol 2: Synthesis of 2'-O-protected oligonucleotides and their deprotection properties under bioreduction.